Mechanisms of Elemental Mercury Transformation on α-FeO(001) Surface from Experimental and Theoretical Study: Influences of HCl, O, and SO.

The reaction mechanisms of a mixture gas of HCl, O, and SO in Hg adsorption on α-FeO(001) surface are clarified by a group of adsorption experiments and theoretical calculations based on the density functional theory. The role of O in removing Hg is greatly influenced by the reaction temperature, meanwhile, the O atom coverage could affect the adsorption performance of Hg. The dissociated O competes with the active sites of Cl species on Fe surface at low temperature, however, at medium temperature HCl and O could simultaneously facilitate the Hg transformation. Combined with the theoretical calculations, the role of SO and the probable pathways in removing Hg are discussed. Lower concentration of SO as well as HCl could dissociate on α-FeO(001) surface, and the intermediates combine with gaseous Hg, forming mercury-sulfur, mercury-chlorine compounds, and so forth. In addition, the different concentrations of SO are also discussed, and the corresponding X-ray photoelectron spectroscopy analysis on contrasted samples is conducted to research the morphological characterization, providing a reliable basis for judging the probable pathways of Hg transformation.